In the packaging of various commodities, it has become desirable to provide some indication as to whether the contents have been tampered with. In such packages, one common expedient has been to use a ring that is connected to the closure of the container and is broken or severed when attempts are made to remove the closure. In one type of such package, that is shown for example in U.S. Pat. Nos. 3,329,290 and 3,784,041, the closure includes an integral pilfer ring that snaps over an annular bead on the container and is fractured or severed from the closure when the closure is removed. In another type of package such as shown in U.S. Pat. Nos. 3,673,761, 4,206,852 and 4,033,472, the closure includes an integral ring which is deformed by heat over an annular bead when the closure is applied to the container, which ring is thereafter fractured or broken from the remainder of the closure when the closure is removed. In U.S. Pat. No. 4,033,472, the closure includes a portion that retains the pilfer ring in position.
Among the objectives of the present invention are to provide a package which has a pilfer ring that will function to indicate that the closure has been removed or tampered with, which does not require any special step in the application thereof to the container, which can be readily manufactured and which effectively provides an indication of tampering or removal of the closure while keeping the retaining ring attached to the closure.
In accordance with the invention, the tamperproof package comprises a container having a neck with external threads formed thereon and a plastic closure comprising a top panel and an integral depending annular skirt, the skirt having integral internal threads formed thereon complementary to the threads on the neck of the container. The container has an annular locking bead positioned axially below the threads. The skirt has a pilfer ring at the lower end thereof connected to the upper portion of the skirt by a plurality of circumferentially spaced integral bridge portions that are located below the threads when the closure is on the container. The ring has a radially inwardly extending annular rib engaging beneath the locking bead of the container when the closure is on the container. One of the bridge portions has a greater cross section than the remainder of the bridge portions such that when the closure is applied to the container, the rib on the pilfer ring snaps over and engages below the locking bead on the container, and when the closure is rotated to remove the closure from the container, the bridge portions are broken except for the bridge portion having the greater cross section such that the pilfer ring remains connected to the closure.